I don't think it's necessarily fair to say that "after X hours, you're not entitled to a refund."
I think of the Mass Effect 3 scenerio. Now, I wouldn't want a refund for that game even if it was available because that was like 40 hours of goodness with 10 minutes of pure shit with the ending. However, the ending really was SO bad that it basically ruined the entire experience for me. After being a die hard fan, I immediately went cold turkey. I replayed ME1 and 2 multiple times, haven't touched ME3 since I finished it. I bought all the DLC in ME1 and 2, didn't buy the DLC for 3 even after hearing good things. I MIGHT get Andromeda, but even now, I'm ehhing on it just because the finale of 3 was just that cancerous for me. It poisoned everything I loved about the series.
Now, like I said, I wouldn't get a refund because I agree that enjoying 99% of the game and then demanding the entire amount of money investement back because of 1% is perhaps unreasonable. However, it does show how it doesn't matter how much hours you put into a game or how you enjoyed those first few hours if, when you put down the controller, you are feeling like you got cheated.
As a disclaimer, I'll say that I never bought into the NMS hype (not for any particular reason, I just didn't see what was so interesting about the game pre-launch besides being pretty), but I've had experiences like many NMS fans where they felt cheated from what should have been something fantastic and instead got something that has fallen vastly short. Not just a little, but a lot. The point here is that when you play a game, even in a pure blind buy, you are putting faith in the game to deliver you an experience that is worth your time.
People say that after 8 hours, you should know what your in for, but the truth is, I've had games surprise me further in than 8 hours. I've books or comics that don't truly get good until a huge investment of time is had. So unless the game is just absolutely atrocious, I am willing to deal with most problems it has so long as I feel I am rewarded for my faith and steadfastness by the end of the journey.
I don't know how long I'd have tolerated NMS before giving up, but I could easily see myself putting in over 10 hours before realizing I was wasting my time with it. I might even go as far as making it all the way to the end, just because I would be willing to give the game a chance to deliver on the hyped up galactic center. It'd be only after I got there, and realized the full extent of the game's betrayal of my faith in it, that I'd be fully outraged at how it didn't live up to expectations.
So while I don't have a dog in this particular fight, I've been in positionswhere I'm excited for a game and willing to go out on a limb based on faith that the game will deliver something good. I don't consider this stupidity or irresponsibility, it's simply courtesy and optimism. I believe every game derserves a shot to get it's shit together and deliver on what good it can. And usually, this works out for me in some way or another. Not with big explosives turn abouts, but it usually accomplishes SOMETHING that makes me think "Well that was worth it". But if the game does fail on such a level that NMS failed many of it's fanbase (and lets face it, many people DO feel their faith in the game has been betrayed on a massive level), I think a refund is fair game, regardless of the hours they've put into it.